The Milwaukee Brewers don't play doubleheaders very often. When they do, they make them count.

Rookie Shane Peterson hit his first career home run, Elian Herrera added his second homer of the day and Ariel Pena got the win in his major league debut as the Milwaukee Brewers completed a sweep of their day-night doubleheader against the Cincinnati Reds with a 7-3 win on Saturday.

"It was a long day, but a good day," manager Craig Counsell said of two games that lasted more than three hours each, plus a one-hour, 33-minute thunderstorm delay. "We played well."

Peterson led off the sixth inning with a 366-foot drive into the right field seats for his second RBI of the game, helping the Brewers extend their winning streak to six games with their first doubleheader sweep since taking two from the Cubs on July 30, 2013, in Chicago.

Herrera broke the game open in the ninth with his seventh homer of the season, a three-run shot.

Milwaukee has won six straight games at Cincinnati.

In the opener of the first doubleheader in history between the Reds and Brewers, Herrera snapped a 6-6 tie with an eighth-inning leadoff home run and Milwaukee went on to an 8-6 win.

Pena (1-0), who joined Milwaukee from Triple-A Colorado Springs on Friday, allowed two hits and two runs with a walk and two strikeouts after taking over for starter Wily Peralta following the delay in the middle of the third inning.

"I'm probably a little too excited," said Herrera, who had the lineup card and game ball. "It wasn't too difficult coming in. Yes, this is the big leagues, but I didn't feel any pressure at all."

Relievers Kyle Lohse, Cesar Jimenez and Corey Knebel combined for four shutout innings before Tyler Thornburg gave up rookie Adam Duvall's second homer in a week.

The Brewers took a 3-0 lead with a one-out rally against Keyvius Sampson (2-3) in the third inning. Domingo Santana and Peterson delivered back-to-back RBI singles and Santana scored from third on Jean Segura's groundout.

The Brewers compiled five hits with three walks and three strikeouts in three innings against Sampson, who hasn't won in four starts since Aug. 13. He believes his problems result from being unable to keep his head going toward the plate.

"When he was going good, he was clustering pitches in the zone," Reds manager Bryan Price said. "Now he's spraying them all around."

Reliever Pedro Villareal, who replaced Sampson after the delay, surprised the holdovers from the crowd of 29,842 by coming up with a two-run double in the fourth - his first career extra-base hit and RBIs.

MAN SHORT

Plate umpire Will Little left the game with because of what was announced as a "family medical issue." Phil Cuzzi moved from second base to behind the plate after the third inning rain delay. Toby Basner moved from third base to second and Gerry Davis, the plate umpire in the opener, took over at third in the nightcap.

RARE OCCASION

The Reds were swept in a doubleheader for the first time since Aug. 28, 2007, at Pittsburgh and were swept at home for the first time since Aug. 17, 1990, to the Pirates at Riverfront Stadium.

TRAINER'S ROOM

Brewers: Matt Garza's start in the opener was his last appearance of the season, manager Craig Counsell revealed between games. Even though he's physically healthy, Garza was shut down so the Brewers can look at other pitchers and hopefully give Garza a fresh outlook on 2016 after a 6-14 season.

Reds: OF Brennan Boesch began his rehab assignment with Triple-A Louisville. The Reds placed Boesch on the 15-day DL on Aug. 31 with a bruised bone in his right ankle.